Adjustable Surgical Instruments and Methods of Use and Fabrication

ABSTRACT

A system for assessing an intervertebral disc space comprises an elongated catheter with proximal and distal ends and an expandable body carried at the distal end of the elongated catheter. The expandable body includes a distal cap portion. The system further includes a mandrel extending through the elongated catheter and the expandable body and attached to the distal cap portion. The mandrel is movable within the elongated catheter and the expandable body to reposition the distal cap portion relative to the distal end of the elongated catheter while the expandable body is positioned within the intervertebral disc space.

BACKGROUND

Degenerated disc disease refers to a syndrome in which a compromiseddisc causes low back pain. Disc degeneration may result in discherniation in which the central portion of the intervertebral disc,known as the nucleus pulposus, may protrude through an opening in thesurrounding fibrous ring, known as the annulus fibrous. A herniatedlumbar disc can push on spinal nerves causing severe, shooting, legpain, numbness, and/or weakness. Discectomy is a surgical procedure inwhich the nucleus pulposus of a herniated intervertebral disc isresected or removed to relieve pressure on the spinal cord and radiatingnerves. Improved tools are needed to allow physicians to evaluate theextent of discectomy that has been performed and to assess theintradiscal space for further procedures such as fusion or arthroplasty.

SUMMARY

In one embodiment of the present disclosure, a system for assessing anintervertebral disc space comprises an elongated catheter with proximaland distal ends and an expandable body carried at the distal end of theelongated catheter. The expandable body includes a distal cap portion.The system further includes a mandrel extending through the elongatedcatheter and the expandable body and attached to the distal cap portion.The mandrel is movable within the elongated catheter and the expandablebody to reposition the distal cap portion relative to the distal end ofthe elongated catheter while the expandable body is positioned withinthe intervertebral disc space.

In another embodiment of the present disclosure, a method for assessingan intervertebral disc space comprises selecting an assessmentinstrument. The assessment instrument includes an elongated catheterwith proximal and distal ends and an expandable body carried at thedistal end of the elongated catheter. The expandable body includes adistal cap portion. The instrument further includes a mandrel extendingthrough the elongated catheter and the expandable body and attached tothe distal cap portion. The method further includes inserting theexpandable body into the intervertebral disc space, extending themandrel to move the distal cap portion distally of the distal end of theelongated catheter, and expanding the expandable body within theintervertebral disc space.

In another embodiment of the present disclosure, a system for assessingan intervertebral disc space comprises an elongated catheter with acentral lumen extending between distal and proximal end portions of theelongated catheter and an expandable body carried at the distal endportion of the elongated catheter. The expandable body includes a distaltip. The system further comprises a mandrel sized to extend through thelumen and the expandable body. The mandrel includes a distal end fixedlyattached to the distal tip of the expandable body and a proximal endextending proximally of the proximal end portion of the elongatedcatheter and including a gripping section. The expandable body has afirst length when the gripping section is in a first position relativeto the proximal end portion of the elongated catheter and has a secondlength, longer than the first length, when the gripping section is in asecond position, closer to the proximal end portion of the elongatedcatheter than when in the first position.

Further aspects, forms, embodiments, objects, features, benefits, andadvantages of the present invention shall become apparent from thedetailed drawings and descriptions provided herein.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a medical device for intervertebral disc assessmentaccording to one embodiment of this disclosure.

FIG. 2 illustrates a partial cross-sectional view of the medical deviceof FIG. 1.

FIG. 3 illustrates an expandable portion of the medical device of FIG. 1disposed in an extended configuration.

FIG. 4 illustrates an expandable portion of the medical device of FIG. 1disposed in a different extended configuration.

FIG. 5 illustrates an expandable portion of the medical device of FIG. 1disposed in different expanded and extended configurations.

FIG. 6 describes a surgical method according to one embodiment of thisdisclosure.

FIGS. 7-8 illustrate deployment of a medical device according to anembodiment of this disclosure.

DETAILED DESCRIPTION

The present disclosure relates generally to the field of intervertebraldisc treatment, and more particularly to systems and methods forevaluating an intervertebral disc space in conjunction with a discectomyprocedure. For the purposes of promoting an understanding of theprinciples of the invention, reference will now be made to embodimentsor examples illustrated in the drawings, and specific language will beused to describe these examples. It will nevertheless be understood thatno limitation of the scope of the invention is thereby intended. Anyalteration and further modifications in the described embodiments, andany further applications of the principles of the invention as describedherein, are contemplated as would normally occur to one skilled in theart to which the disclosure relates.

Referring first to FIG. 1, a medical device for intervertebral discassessment and treatment is indicated generally by the numeral 10. Thedevice 10 includes a catheter 12 having a proximal end 14 and a distalend 16. A lumen extends through the catheter between the ends 14, 16. Anexpandable body 18 is carried by the distal end 16 of the catheter and aconnection assembly 20 is carried by the proximal end 14 of thecatheter.

In this embodiment, the connection assembly 20 is a Y-port connectionassembly with a tubular section 22 coaxially aligned with the catheter12 and a tubular section 24 obliquely intersecting the tubular section22. The tubular section 22 is connected to a material deliveryinstrument 26 via an adapter 28. A suitable material delivery instrumentmay be, for example, a syringe for containing an inflation medium to bedelivered to the expandable body 18. The adapter 28, which may be atwo-way stopcock, is configured to control the flow of the inflationmedium between the material delivery instrument 26 and the catheter 12.

As shown more clearly in FIG. 2, the expandable body 18 comprises anexpandable tube 30 connected to and extending between the distal end 16of the catheter 12 and a cap portion 32. As will be described in greaterdetail below, the cap portion 32 may be bonded to the expandable tube30, but in alternative embodiments, the cap portion may be an integrallyformed closed distal tip or a self-sealed distal tip of an expandabletube or balloon.

A mandrel 34, having a distal end 36 and a proximal end 38, extendsthrough the expandable tube 30, the lumen of catheter 12, and thetubular section 22 of the connection assembly 20. The mandrel 34 ismovable generally linearly along an axis defined through thosecomponents of the device 10. The distal end 36 of the mandrel 34 isconnected to the cap portion 32, and the proximal end 38 is fitted witha handle 40. The connection between the distal end 36 of the mandrel 34and the cap portion 32 may be a fixed connection using, for example, anadhesive, a weld, a mechanical connection, or other type of rigid bond.In certain embodiments, an ultra-violet light activated glue may be asuitable adhesive. In alternative embodiments, the mandrel and capportion may be connected by other types of connections which allow thedistal end 36 of the mandrel 34 to remain attached to the cap portion 32while the mandrel is both extended and retracted within the catheter 12.Other types of suitable connections may include a movable joint,including for example, a ball-in-socket joint or a disconnectable jointsuch as a threaded connection. In embodiments where the cap portion isan integrally formed distal tip of the expandable body, the mandrel maybe attached directly to a distal surface of the expandable body.

The mandrel 34 may be formed from a material sufficiently rigid tocontrol movement of the cap portion 32 within uninflated, underinflated,and fully inflated expandable bodies. A suitable mandrel material maybe, for example, 0.025 in. stainless steel wire. The mandrel may,alternatively, be formed from a tubular member. As shown in FIGS. 3-5,the mandrel 34 may be used to adjust the length of the expandable body18. FIG. 3, for example, depicts an underinflated expandable body 18having a length L1 between the distal end of the catheter 12 and capportion 32. Sliding the mandrel 18 moves the cap portion 32 further awayfrom the distal end of the catheter 12 and elongates the expandable body18 to a length L2 as shown in FIG. 4. The elongation of the expandablebody 18 may occur by stretching, unfolding, unrolling, or any othermethod of lengthening the expandable body.

As shown in FIG. 5, the mandrel 34 may slide within the catheter 12 andbe used to selectively adjust the length of the inflated expandable body18 to assess space within a body cavity. For example, the expandablebody 18 may have a length L3 of approximately 10 mm prior to elongationwith the mandrel. The mandrel 34 may be used to lengthen the expandablebody 18 to an extended length L4 which may be approximately 65 mm orgreater. Thus, in some embodiments, the use of the mandrel may elongatethe expandable body between 0 and 55 mm. It is understood that mandrelsand their associated expandable bodies may be provided in a variety ofsizes, and the dimensions provided are mere examples. As will bedescribed in greater detail below, the size of the intervertebral discspace and the size of a cavity created by prior discectomy proceduresmay limit the extension of the mandrel and the length of the expandablebody.

Suitable materials may be selected for the fabrication of the componentsof the disc assessment device 10. The catheter may have a shaft that isflexible and resistant to kink formation. The materials for the cathetermay also be selected to facilitate advancement of the expandable body.The catheter can be constructed, for example, using standard flexible,medical grade plastic materials, like vinyl, nylon, polyethylenes,ionomer, polyurethane, polytetrafluoroethylene (PTFE),polyetheretherketone (PEEK), and/or polyethylene tetraphthalate (PET).An elastomeric material, polyether block amide, which is offered byArkema of Puteaux, France under the tradename Pebax may be suitable forsome embodiments. The catheter can also be fabricated from more rigidmaterials to impart greater stiffness and thereby aid in itsmanipulation. More rigid materials that can be used for this purposeinclude stainless steel, nickel-titanium alloys, and other metal alloys.The catheter may also be constructed using braided or woven materials toimpart greater stiffness and withstand torque.

The expandable tube may be formed of a highly compliant, elastomericmaterial capable of generally conforming to surrounding tissue when theexpandable body 18 is inflated. Suitable materials may include silicone,latex, polyurethane, or neoprene. In some embodiments, a thermoplasticrubber elastomer offered by AdvanSource Biomaterial Corporation ofWilmington, Mass. under the tradename ChronoPrene may be particularlysuitable. Alternatively, the expandable tube may be formed of amaterial, such as vinyl, nylon, or PET, having relatively inelasticproperties.

The expandable tube 30 may be attached to the distal end 16 of thecatheter 12 and the cap portion 32 using a bonding material 42. Forexample, the bonding material may be an adhesive, a melt bond material,or flexible, heat shrinkable tubing. A suitable bonding material may be,for example, heat-shrinkable tubing offered by Tyco ElectronicsCorporation of Berwyn, Pa. under the tradename Altera MT5000. Although asingle bonding material may be used to bond the catheter 12 to theexpandable tube 30, more than one bonding material may provide greateradherence. For example, the use of a medical grade adhesive appliedbetween the tube and the catheter together with an externally appliedshrink tubing may provide improved gripping force. Medical gradeadhesive may also be applied at the proximal and distal edges of theexpandable tube 30 to minimize slipping of the bonding material 42.Suitable medical grade adhesive may include products that cure in thepresence of ultraviolet light.

To permit radiographic positioning of the expandable body 18, radiopaquemarkers 44 (FIG. 2) may be applied to the expandable body or thecatheter. The markers 44 may be bands secured to the catheter 12 and/orcap portion 32 by crimping, swaging, or other techniques known in theart. A platinum-iridium alloy may be a suitable material for fabricatingradiopaque markers. To aid the in the positioning of the expandable body18 without the fluoroscopic guidance, distance markers 46 may be printedor otherwise formed on the catheter 12 to permit visual monitoring ofthe catheter insertion depth.

As described in FIG. 6, the device 10 may be used by a practitioner toassess space within an intervertebral disc according to the method 50.At step 52, a conventional discectomy procedure may be performed toremove all or a portion of a nucleus pulposus from an intervertebraldisc space D located between vertebral bodies V1 and V2 (FIGS. 7-8). Thedisc space D may have a distal region DD and a proximal region DPrelative to an access location. To determine if further discectomy isneeded and to determine the location for any additional discectomy, thedisc assessment device 10 may be used.

At step 54, the material delivery instrument 26 may be prepared. Forexample, an empty 20 cc locking syringe may be attached via luer lock tothe stopcock 28. The stopcock 28 may be attached to the tubular section24 of the connection assembly 20, also via a luer lock connection.Optionally, the expandable body 18 and catheter 12 may be vacuumed priorto use or flushed with inflation medium to eliminate or minimize airbubbles when inflation medium is later added to inflate the expandablebody. The stopcock 28 may be used to retain the vacuum the expandablebody 18 and catheter 12 while the syringe 26 is detached and filled withan inflation medium such as radiopaque contrast media. The syringe 26may be reattached to the stopcock 28.

At step 56, the expandable body 18 and catheter 12 may be introducedinto a cannula 70 which provides access to the intervertebral disc spaceD located between vertebral bodies V1 and V2. In this embodiment, apercutaneous and unilateral access technique is used, but in alternativeembodiments an open procedure or multilateral approach may be used. Theplacement of the expandable body 18 and the catheter 12 may be guided byfluoroscopy.

At step 58, the mandrel 34 may be extended to move the cap portion 32toward the distal area DD of the intervertebral disc space D while aportion of the expandable body 18 remains near the proximal area DP ofthe intervertebral disc space. To extend the mandrel 34 and elongate theexpandable body 18, the practitioner may grip the handle 40 and push ittoward the proximal end 14 of the catheter 12. The mandrel 34 may beextended until the practitioner senses contact with tissue orfluoroscopically visualizes sufficient elongation of the expandable body18. As the mandrel is extended, the expandable body may stretch, unroll,unfold, or otherwise become elongated. The mandrel may extend linearly,generally along an axis defined through the catheter lumen.

The mandrel may be freely slidable within the catheter as described, butin alternative embodiments, the movement of the mandrel may be morediscrete or controlled. For example, the mandrel may be configured tothreadably engage the catheter so that rotation of the handle advancesthe mandrel and elongates the expandable body. In another alternative,the mandrel may be advanced along ratchet positions which serve tocontrol the linear movement and of the mandrel.

At step 60, the expandable body 18 is then gradually inflated underfluoroscopy using radiopaque contrast media. The practitioner May detectincreasing resistance to inflation as the expandable body 18 expands andmay stop further inflation when the expandable body 18 contacts thetissue remaining in the disc space D after the discectomy.

At step 62, the practitioner may assess whether further discectomy isnecessary. Under fluoroscopy, the practitioner may determine whether thesufficient discectomy has been performed by determining whether theexpandable body 18, in the inflated condition, contacts the endplates ofthe superior and inferior vertebral bodies and whether the expandablebody has inflated past the midline of the contralateral portion of thedisc. The discectomy and assessment procedures may be repeated until thepractitioner is satisfied with the extent of discectomy. After finalassessment is performed, the practitioner may compare the initial volumeof the inflation media in the material delivery instrument 26 prior toexpansion with the final volume of the inflation media in the materialdelivery instrument after expansion. The difference in volumes can beused to provide a volumetric estimate of the extent of the discectomyprocedure which can be used to determine the amount of bone graft orother filling material to be implanted for fusion.

As described, the mandrel 34 may be extended to elongate the expandablebody 18 prior to expansion. Alternatively, as shown in FIGS. 7-8, themandrel 34 may be extended toward the distal area DD of the disc space Dwhile the expandable body 18 is partially or fully inflated, until theexpanded expandable body substantially fills the disc space.

It is understood that the device 10 is not limited to use within anintervertebral disc space, but could be used to assess the size andconfiguration of cavities in other regions of a body including regionswithin vasculature, organs, other soft tissue, or bone, including avertebral body.

While the present invention has been illustrated by the abovedescription of embodiments, and while the embodiments have beendescribed in some detail, it is not the intention of the applicant torestrict or in any way limit the scope of the invention to such detail.Additional advantages and modifications will readily appear to thoseskilled in the art. Therefore, the invention in its broader aspects isnot limited to the specific details, representative apparatus andmethods, and illustrative examples shown and described. Accordingly,departures may be made from such details without departing from thespirit or scope of the applicant's general or inventive concept. In theclaims, means-plus-function clauses are intended to cover the structuresdescribed herein as performing the recited function and not onlystructural equivalents, but also equivalent structures.

1. A system for assessing an intervertebral disc space comprising: anelongated catheter with proximal and distal ends; an expandable bodycarried at the distal end of the elongated catheter and including adistal cap portion; a mandrel extending through the elongated catheterand the expandable body and attached to the distal cap portion, whereinthe mandrel is movable within the elongated catheter and the expandablebody to reposition the distal cap portion relative to the distal end ofthe elongated catheter while the expandable body is positioned withinthe intervertebral disc space.
 2. The system of claim 1 wherein themandrel is fixedly attached to the distal cap portion.
 3. The system ofclaim 1 wherein the mandrel is movable within the elongated catheterduring expansion of the expandable body.
 4. The system of claim 1wherein the expandable body further comprises an expandable tubeattached between the distal end of the elongated catheter and the distalcap portion.
 5. The system of claim 1 wherein the mandrel includes ahandle extending proximally of the proximal end of the catheter.
 6. Thesystem of claim 1 wherein the mandrel includes an elongated wire member.7. The system of claim 1 wherein the mandrel includes an elongatedtubular member.
 8. The system of claim 1 further including a connectionassembly connected to the proximal end of the elongated catheter andcomprising a first tubular portion sized to slidably receive a portionof the mandrel and a second tubular portion configured for connection toa material delivery device.
 9. The system of claim 1 further including acannula sized for through passage of the expandable body and at least aportion of the elongated catheter.
 10. The system of claim 1 wherein theexpandable body includes at least one radiopaque marker located near aproximal end of the expandable body and at least one radiopaque markerlocated near a distal end of the expandable body, wherein the radiopaquemarkers are movable relative to one another with the movement of themandrel.
 11. A method for assessing an intervertebral disc spacecomprising: selecting an assessment instrument including an elongatedcatheter with proximal and distal ends, an expandable body carried atthe distal end of the elongated catheter and including a distal capportion, and a mandrel extending through the elongated catheter and theexpandable body and attached to the distal cap portion; inserting theexpandable body into the intervertebral disc space; extending themandrel to move the distal cap portion distally of the distal end of theelongated catheter; and expanding the expandable body within theintervertebral disc space.
 12. The method of claim 11 wherein theexpandable body further includes a tubular wall and wherein the step ofextending the mandrel includes stretching the tubular wall along an axisdefined through the elongated catheter.
 13. The method of claim 11wherein the step of extending the mandrel is conducted concurrently withthe step of expanding the expandable body.
 14. The method of claim 11further comprising positioning a cannula at an opening to theintervertebral disc space and extending the expandable body and at leasta portion of the elongated catheter through the cannula.
 15. The methodof claim 11 wherein the step of expanding the expandable body includesinflating the expandable body with an inflation medium.
 16. The methodof claim 11 further wherein the step of extending the mandrel includesextending the mandrel until the distal cap portion contacts tissuewithin the intervertebral disc space.
 17. The method of claim 11 furthercomprising determining a volume of inflation media used to expand theexpandable body.
 18. A system for assessing an intervertebral disc spacecomprising: an elongated catheter with a central lumen extending betweendistal and proximal end portions of the elongated catheter; anexpandable body carried at the distal end portion of the elongatedcatheter and including a distal tip; a mandrel sized to extend throughthe lumen and the expandable body, the mandrel including a distal endfixedly attached to the distal tip of the expandable body and a proximalend extending proximally of the proximal end portion of the elongatedcatheter and including a gripping section; wherein the expandable bodyhas a first length when the gripping section is in a first positionrelative to the proximal end portion of the elongated catheter and has asecond length, longer than the first length, when the gripping sectionis in a second position, closer to the proximal end portion of theelongated catheter than when in the first position.
 19. The system ofclaim 18 wherein the difference between the first and second lengths isgreater than 20 mm.
 20. The system of claim 18 wherein the differencebetween the first and second lengths is greater than 50 mm.
 21. Thesystem of claim 18 further comprising a connector assembly attached tothe proximal end portion of the elongated catheter, the connectorassembly including a first tubular portion coaxial with the centrallumen and sized for passage of the mandrel therethrough and a secondtubular portion disposed at an oblique angle to the first tubularportion and including a fitting sized to connect with a materialdelivery device.
 22. The system of claim 18 wherein the expandable bodyincludes an expandable wall integrally formed with the distal tip. 23.The system of claim 18 wherein the distal tip includes a cap portion andthe expandable body further includes an expandable tubular wall bondedbetween the cap portion and the distal end portion of the elongatedcatheter.